The dosing of drugs are carried out in a number of different ways in the medical service. In the medical service there are today for dry powders and aerosols a number of different inhalers in use, which all have as a common object to supply a substance to the lung through the patients own inspiration. The substances or mixtures of substances today used in the medical service are all developed to be supplied by means of a deep breath, which means high local velocities, which in turn means that a certain amount of the substance will stick to the airways and to the inhaler. The amount of substance in this way sticking also varies from individual to individual due to the individual way of breathing. This low efficiency and low dosing precision either means an increased risk for side effects if a too large dose is supplied, or risk for low effect if a too small dose is supplied. Thus, it is of the utmost importance that the dosing can be coordinated with the inspiration when using inhalers.
A method of improving the efficiency of an inhaler is disclosed in two patent documents, WO-9419042 and WO-9515353. The method means that the substance (powder or aerosol) is being electrically charged after the dosing and the distribution of the substance to the lung is in this way improved. The static electric charging of the substance is said to imply a more even distribution of the substance in the air stream at inspiration and therefore not sticking on to the inhaler or the airways to the same extent. The patent discloses a normal mechanical dosing. The inhalers of today, the usage of which increase strongly, accordingly do have a number of disadvantages which after all limit their efficiency and usage. The following list of items exemplifies some of these disadvantages:
A varying concentration of substance in the inhaled air. PA1 A very large proportion of the substance sticks on to the inhaler and/or the airways. PA1 Deviations in the inspiratory process can result in great deviations in the dose emitted to the lung. PA1 Today, only a small number of substances can be used in inhalers according to prior art. PA1 The amount of substance emitted to the lung can vary from patient to patient and between different dosing occasions. PA1 Inhalers according to prior art are generally not meant for repeated reuse.